1894.] NEW-YORK MICROSCOPICAL SOCIETY. 37 



cannon and may be heard many miles. The charges from these 

 " guns" are fired against an iron target about thirty feet distant, 

 leaving a spongy mass which is then converted by chemical treat- 

 ment into paper. Besides the mangling of paper stock by the 

 various pulp-making methods, there are still the several processes 

 of finishing, such as bleaching, sizing, and moulding the pulp by 

 means of wire gratings, upon which the setting or hardening pulp 

 rests ; a portion of these screens, with figures or names placed in 

 them by means of thinner wires, producing the "water-markings " 

 commonly seen on writing papers. 



In addition to these we have the calendering, glazing, filling, 

 and numerous oiher finishing processes, with which I will not 

 further weary you. 



Having now seen these several constituents of paper variously 

 torn, cut, beaten, mangled, shot out of " guns," ground up, dis- 

 solved by chemical means, and many of these substances com- 

 pletely transformed from their original condition and the ap- 

 pearances with which we are familiar, how are we to determine 

 what they are ? When we consider the great variety of materials 

 used in the manufacture of paper, and yet know that all of them 

 consist of cellulose, which gives a similar reaction chemically, we 

 find that the chemist is debarred from positively identifying any 

 admixture of pulps or finished paper, although he can detect 

 *' mechanical " wood pulp unmixed, as we shall see later, by the 

 color demonstrations on the papers, as heretofore mentioned and 

 here exhibited ; but beyond this stage chemical tests become un- 

 reliable. 



We see, therefore, why almost the entire determination of ad- 

 mixtures in paper rests with the microscopist. 



It is easy to recognize under the microscope the ordinary 

 materials from which paper is manufactured, such as linen, cot- 

 ton, various woods cut in thin sections, etc., when each of these 

 substances is in its natural condition and properly mounted for 

 microscopical observation. 



Here are displayed before you under magnification not only 

 preparations of the actual materials — flax, cotton, etc. — but also 

 a number of photomicrographs of the same preparations dis- 

 tinctly exhibiting the details (Plate 39, Figs, i, 2,5 ; Plate 40, 

 Figs. 7, 9). In addition to these examples of the simple fibres 



